PROJECT SUMMARY Humans and other social animals use vocalizations to communicate during a variety of social interactions, such as maintaining positive relationships, caring for offspring, and fighting. Speech or animal vocalizations produced during one social interaction may have a different meaning when produced during a different social interaction. This social context is important for understanding the meaning of vocalizations. This proposal seeks to understand brain mechanisms that analyze the social context surrounding the meaning of speech and other communication sounds. The proposal focuses on the basolateral amygdala (BLA), an important brain area for assigning value to the external senses, and also for processing many features of social interactions. The BLA responds to vocalizations, and the responses can be modified by contextual cues from the other senses. The project will test the general hypotheses that social context influences the BLA's analysis of acoustic communication signals, and that these effects are based on cellular properties of individual neurons. Aim 1 will test how social context influences the responses of BLA neurons to positive and negative vocalizations in the presence or absence of a familiar animal. The results from this Aim will show how the BLA influences vocalization processing over timescales of seconds to minutes. These results may be important for disorders such as schizophrenia and autism, which involve deficits in both communication and social information processing. Aim 2 will study cellular properties of neurons in the BLA and relate these to responses to positive and negative vocalizations. It will further test whether long-term social stress (in days) changes both the cellular properties and the responses to vocalizations. The results of this Aim will lead to better understanding of the diverse ways that BLA neurons can respond to sounds. These results are expected to reveal mechanisms by which stress can change responses to meaningful sounds, indicating a potential neuronal mechanism underlying the aversive response to neutral sounds in PTSD.